The Postmortem Pathology Section provides a complete, 24 hour per day, 365 days per year service in autopsy pathology for the Clinical Center. All patients on protocols for any of the Institutes or the Clinical Center may have an autopsy performed by the Laboratory of Pathology at the discretion of the principle investigator. The results from autopsies are used to assess treatment response, to answer clinical questions at the time of death, to identify pathology that was unknown or misdiagnosed prior to death, and to provide for hospital and protocol quality assurance. In addition, when the use and study of human pathological material is requested by research staff of any of the categorical institutes, the Postmortem Section makes every effort to collaborate with and/or supply the researchers with the human tissues upon approved request. (The Laboratory of Pathology has a standard procedure for tissue requests.) The autopsy material is utilized by NIH staff and fellows for research projects involving clinicopathological correlation and characterization of disease processes. Currently, several collaborative projects are on-going: clinical-pathological studies in dementia; culture of tumor cells from post-mortem tumor specimens following rapid autopsy; brain stem gliomas; MRI correlations with normal tissue and de-myelinating disease (multiple sclerosis); investigation into non-HIV immunodeficiencies and complications of graft-versus-host disease. A partial database of major autopsy findings from 1953 through the present is available and all findings from March, 1999 on are available on-line through the Laboratory of Pathology's Information System. This system contains the full text of all autopsy reports. Texts of final reports are also available in the Clinical Research Information System (CRIS) after sign-out. In addition to its primary clinical responsibilities and research support function, the Post-mortem Pathology section is responsible for training pathology residents in the art and science of autopsy pathology. Diseases with deaths investigated in this fiscal year include AIDS, hematological malignancies, non-heatological malignancies (particularly thoracic and urological tumors), gliomas, and non-AIDS immunodeficiencies..